Lost my wifi hardware connection after installing Yosemite.

Installing the OS is very unlikely to have damaged your wireless..

Software and particularly a buggy as !heaven one like Yosemite has simply failed to load the driver.

Go into system information and check if the card is there. I would be hugely surprised if it isn't.

You can also run hardware test by booting to recovery.

See Using Apple Hardware Test - Apple Support

However to get it running I am not so sure..

Do you really need to do a clean install of the OS..

so you will need to read up on that. If there are other ways to get the card going again.

Did you run the hardware test??

It is too much of coincidence that the wireless stops working right when you install OS.

What model exactly is your MBP?

Let me suggest if you have any applecare ring Apple.. this is not an uncommon issue.

Please see this very long thread.. alot of people are killing their wireless. Especially in older laptops.

Re: OSX Yosemite Wifi issues

There is a bunch of suggestions.. none are silver bullet .. but some have got it fixed.

Here are the most prevalent solutions available: From Nicknish

1. Creating a New Wi-Fi Service (this solution worked for me!)
   • Copy and paste these instructions, because you'll be disconnected from the Internet and you'll need to reboot.
   • Go into your Network Preferences > Select Wi-Fi Service (in the list in the left column) > Click on the options (cog icon) > Select "Make Service Inactive" > Select Apply.
   • Select the same Wi-Fi Service > Delete It ( – ). Reboot.
   • Return to Network Preferences > Create a New Service ( + ).
   • Inside the prompt select Wi-Fi under Interface, name the Service Name something other than Wi-Fi. (I named mine Wi-Fi2. Apparently if you retain the previous Wi-Fi name the WiFi dropping will return on reboot.) > Click Create.
   • Click Apply.
2. Delete and Reconnect to your Preferred Network

   Go into your Network Preferences > Advanced > Select Your WiFi Network and Delete It ( – ). Reconnect to it.

3. Delete Bluetooth.plist

   Finder > Go (on your toolbar) > Computer > HD > Library > Preferences > Delete your Bluetooth.plist. Reboot.

4. Delete SystemConfiguration

   Finder > Go (on your toolbar) > Computer > HD > Library > Preferences > Delete your SystemConfiguration. Reboot.

5. Reset PRAM

Reset your PRAM (Haven't tried it myself so I don't feel right instructing others how to do it, sorry!).